4 Ray Gun's on Little Resistance Easter Egg
After crashing on the beach, radio in a rocket strike on the Japanese defenses. Once the beach is clear run to the right side of the beach. You will notice a few craters, there are the triggers for the Easter Egg. To unlock it you will have to walk through 4 craters. First walk through the large crater that is full of water, then turn left and walk through the small crater that is full of water, turn left again and walk through the small dry crater, then finally turn left and walk into and stand in the huge crater full of water. Wait about 10 seconds and a weird voice will start talking, and your screen will start shaking. Then 4 statues will come up through the ground. Each statue will be holding a ray gun.

Video Tutorial:

Ray Gun
First off, type:

/devmap nazi_zombie_prototype
/give ray_gun

If you do this, you will get a ray gun on zombie mode (on other modes I would not know).